An inquest into her death concluded that she was unlawfully killed and died as the result of a stab wound which severed her jugular vein.

During the hearing, it emerged that 15-year-old Cornick had told a number of pupils about his plan to kill three teachers and showed some of them the kitchen knife he had taken from home to use as a weapon.

But none of those pupils raised the alarm with their teachers or other adults.

Concerns arising from this evidence are set out in a Report to Prevent Future Deaths sent to education watchdog Ofsted on November 22.

In it, Mr McCloughlin said: "The need to prevent weapons such as knives being brought into schools in the UK is axiomatic.

"How schools perceive the risks associated with weapons and manage them, appears to be the subject of widespread variation."

The report noted that Cornick was jailed after admitting Mrs Maguire's murder and is now serving life sentence with a minimum term of 20 years.

Mr McCloughlin said: "Prior to the attack, he had told other children in his class of his intention to kill three teachers and showed some of them the large kitchen knife he had taken from home to use a weapon.

"None of the 10 children concerned informed a teacher or other adult of his intention or that he was in possession of a knife."

The inquest also heard Ofsted inspectors had visited the school 10 months before the attack, spending two days there.

No indication was given to them from staff, parents or pupils that knives were a problem and the inspector's report went on to say pupils felt "very safe".

Mr McCloughlin noted that inspections already consider the issue of safety, but inspectors inevitably have to prioritise what aspects of a particular school will be scrutinised.

Urging action, he said: "In order to give greater prominence to the need to control any weapon being brought into school, Ofsted are asked to consider making it mandatory for their inspectors to review and report on the way a school manages the safety of its pupils and staff and protects them from risk of violent attack.

"In this way, Ofsted may be able to contribute to the dissemination of good practice, for example, by published a prohibited items list and reinforcing the need for children to report anything untoward to a teacher."

Ofsted had a duty to respond to the report by January 17, setting how action taken or proposed to be taken along with a timetable for action.

If the education watchdog decides not to take action, it must explain to the coroner why it is choosing not to do so.